Free DNS Lookup, IP Geolocation & Network Tools
DNSX is a free set of DNS lookup, IP geolocation, SSL, WHOIS and email diagnostic tools. Every tool has a web page and a JSON URL you can call with curl.
What can you check with DNSX?
DNS records, IP addresses, certificates, domain registrations and mail configuration
DNS Lookup
Query A, AAAA, MX, TXT, CNAME, NS and other records from Google, Cloudflare, Quad9, OpenDNS or the authoritative nameservers.
IP Lookup
Geolocation, ASN, organization and RDAP registration data for any IPv4 or IPv6 address.
SSL Checker
Verify a certificate, see when it expires, and inspect the chain the server sends.
WHOIS Lookup
Registrar, creation and expiry dates, nameservers and status codes for any domain.
Email Tools
Check MX records, SPF, DMARC and DKIM configuration, and blacklist status.
Security Tools
Generate passwords, passphrases and hashes, and share secrets through encrypted one-time links.
Five resolvers side by side
Compare Google, Cloudflare, Quad9, OpenDNS and the authoritative answer in one view
Authoritative nameserver queries
Ask the zone’s own nameservers directly and skip every cache
JSON from every tool
Every tool answers curl with JSON, ready for scripts and monitoring
200 free lookups a day
No account, no API key, no signup form
Works from the Command Line
Every tool has a URL that returns JSON. Call it with curl, no API key needed.
$ curl https://api.dnsx.dev/ip/my-ip
{
"ip": "203.0.113.42",
"hostname": "example.isp.net",
"geo": {
"country": "United States",
"city": "San Francisco",
"timezone": "America/Los_Angeles"
},
"asn": {
"number": "AS12345",
"name": "Example ISP"
}
}All DNSX tools
Every lookup page on the site. Each one also answers as JSON.
DNS lookups
Email diagnostics
IP, SSL and WHOIS
Security tools
What is DNSX?
DNSX is a free set of network diagnostic tools for developers, system administrators and IT professionals. It covers DNS lookups, IP geolocation, SSL certificate checks, WHOIS and email authentication, through a web interface at dnsx.dev and a JSON API at api.dnsx.dev that use the same family and tool names.
Every tool works from the command line. A curl request to any api.dnsx.dev URL returns JSON, so the same checks fit into shell scripts, CI pipelines and monitoring jobs. There is no account and no API key. Each IP address gets 200 lookups a day.
Available Tools
DNS Lookup queries records from Google, Cloudflare, Quad9 and OpenDNS, or from the domain's own authoritative nameservers. It supports A, AAAA, MX, TXT, CNAME, NS, SOA, SRV, NAPTR and CAA records. Compare All puts the five answers side by side to show propagation problems, and MX and NAPTR lookups draw the full resolution chain with the location of each host.
IP Lookup returns the geolocation, ASN, organization and RDAP registration data for any IPv4 or IPv6 address, and flags addresses that belong to known hosting providers or VPN services. The What Is My IP page shows your own IPv4 and IPv6 address.
SSL Checker connects to a domain on port 443 and reports the certificate's validity, expiry date, chain, negotiated TLS version and Subject Alternative Names, with a grade from A+ to F.
WHOIS Lookup retrieves the registration record for a domain: registrar, creation and expiry dates, nameservers and status codes, with the raw WHOIS text available as well.
Email Tools check a domain's MX records, validate its SPF record, read its DMARC policy, fetch DKIM keys by selector and look the mail server up on DNS blocklists.
Security Tools include a random password generator, a Diceware passphrase generator, a hash generator (MD5, SHA-1, SHA-256, SHA-512, bcrypt) and a one-time secret link encrypted in the browser with AES-256-GCM.